1. Field of the Invention
The present invention provides a data reading and image processing system using a compact disc storage device and, more particularly, provides two separate CPU (central processing units) systems to enable parallel processing and control of a music and video entertainment system that provides game play with operator interface.
2. Description of Related Art
Video game systems have been extremely popular in providing interactive game play with an operator. Generally, these video game systems have used a microprocessor-based controller that can be connected to a television set and can receive ROM cartridges for providing game play on the video screen with operator controls enabling an interaction with the play of the game. While these game systems have proven to be extremely popular, there has been an increasing demand for more complex game play and more detailed video images. As a result, video game systems have sought to use the increased storage capacity of optical compact disc ROMs (CDs), and have also sought to expand the entertainment possibilities, such as the reproduction of music by a CD player that can be used for not only storing video images, but also the conventional music data associated with a CD player.
In the conventional image processing systems using a CD, one CPU system is used for controlling both the reading of image data and the processing of the image data for image display. As a result, when image data processing or image display is being carried out, other processing and control operations cannot be carried out. As a consequence, the processing speed is substantially decreased, and the capacities of the expanded memory of the CD-ROM is limited. While the compact disc was originally a medium partially established for recording sound, its capability of recording a much larger amount of information than conventional recording media in the form of a digital recording lends itself to recording information other than audio information, such as video information, etc. When used in a television game system, the video information that is stored on the CD-ROM is accessed throughout the progress of the game. Thus, video information that is stored on a CD-ROM must be read out and used as video images of the game, depending upon the various game play options that can be established by the operator's skill and choices.
While the CD-ROM permits a TV game machine to provide a much better quality of display of video images, there has been a limitation in its adaptability to the conventional data reading and imaging processing systems that have been used in this field. As can be appreciated, TV game entertainment systems are relatively competitive, and price limitations impose serious constraints on the hardware components that can be utilized.
Another problem that has occurred exists when the CD operation requires a video display on the TV picture or CRT, such as when various operator instructions must be input into the system. In a play action mode, it is difficult to switch to an operator menu while the CD graphic image is being displayed. Usually in the conventional operation, in order to switch, the CD operation that is currently in play must be stopped, and an operational picture or menu is displayed. Only after the operation with that menu is completed can the game play or CD graphic image be again displayed. Further, when a particular CD program is to be selected, e.g., a program selection menu in the conventional scheme, the display can be made only for a presubscribed number of programs, and there is a limitation on the number of programs that can be assigned or the degree of complicated instructions that can be implemented.
FIG. 3 shows a conventional CD data read and image processing device with data stored on a CD-ROM being read out for processing. CPU 30 controls both a CD-ROM drive unit 32 for reading the data recorded on the CD-ROM and an image processing unit 34 for displaying the data recorded on the CD-ROM as video images. The video image processed by image processing unit 34 is displayed on a TV screen 36. In order to retain the recording data of the CD-ROM for operational processing, CPU 30 has a random access memory 38.
CD-ROM drive unit 32 can read the data from CD-ROM at a rate of 2048 bytes per 1/75-second. However, in order to display a video image using image processing unit 34, it is necessary to process the read data at a different synchronization speed of 1/60-second in the case of an NTSC video format. As the synchronization timing of CD-ROM drive unit 32 and image processing unit 34 are different from each other, there are resulting problems related to the operation of the CD data read and image processing system.
The operation of the conventional CD data read processing device may be further explained with reference to FIGS. 4-6. In FIGS. 4 and 5, the operation is carried out with a priority set for a CD interruption from CD-ROM drive unit 32 over the video interruption from the image processing unit 34. The image data of 2048.times.5 bytes (1 scene) inputted in five cycles from the CD-ROM in 1/75-second for each cycle are outputted as a video image in four cycles by the image processing unit 34.
As shown in FIG. 4, because the CD interruption from CD-ROM drive unit 32 is set with priority, data from CD-ROM is stored in buffer area A of memory 38 at a rate of 2048 bytes per 1/75-second. On the other hand, image processing unit 34 generates a video interruption for processing the data stored in buffer area B of memory 38 at a rate of 2560 bytes per 1/60-second to form a video image. If the read control of CD-ROM drive unit 32 has not ended, data processing is carried out by image processing unit 34, only after the CPU 30 is released from the read control mode.
In addition, as the busy time of CPU 30 is long due to image processing unit 34, when CD interruption is generated before the end of data processing by image processing unit 34, such as after 4/75-second, CD interruption is set as priority, and CD-ROM read control by CD-ROM drive unit 32 is carried out by CPU 30. As shown in FIG. 4, data processing by image processing unit 34 is interrupted.
When the busy time of CPU 30 for image processing unit 34 becomes even longer, as shown in FIG. 5, interruption of data processing by image processing unit 34 takes place even more frequently (after 3/75-second, 4/75-second).
Consequently, it is considered to let the video interruption from image processing unit 34 take priority over the CD interruption from CD-ROM processing unit 32. When the busy time of CPU 30 for image processing unit 34 is short, during the period when CPU 30 is not busy for image processing unit 34, CD-ROM read control by CD-ROM drive unit 32 can be carried out. However, as shown in FIG. 6, when the busy time of CPU 30 for image processing unit 34 becomes longer, the CD-ROM read control by CD-ROM drive unit 32 interrupts after, say, 1/60-second by video interruption.
Thus, the prior art is still seeking to solve the problems of the discrepancy in synchronization timing of the CD-ROM drive unit and the image processing in an economical manner and further to facilitate a switching of the operational picture being played on the video screen so they can be switched with a CD graphic picture and a selection of programs with the CD can be carried out by the operator in an efficient manner.